Electrical regenerative brakes are an essential component in all modem electric and hybrid vehicles. During regenerative braking the kinetic energy of the vehicle is converted into electrical energy and stored for future use. Such energy savings have become important due to increasing fuel costs and stringent automobile emission norms. Added to this is the increasing load of in-car electronics. HVAC (Heating, Ventilation and Air-Conditioning), infotainment devices, and safety & comfort systems contribute towards the majority of the electrical power consumption in cars. Regenerative braking is always used in combination with conventional braking systems.
In an electrical regenerative braking coils and permanent magnets are placed in the wheel of a vehicle. When the brakes are applied the circuit through the coils is completed. According to Faraday's law a current is generated in the coils due to the rotational motion of the wheel. The current thus generated opposes the motion of the coils in the wheels according to Lenz's law, hence producing a braking effect. At the same time the current in the circuit is used to charge the batteries/super-capacitors.
It may be observed that in existing electrical regenerative brakings the magnetic field existing across the coils remain constant with time. Due to this reason the current solutions for regenerative braking are not effective if used at lower speeds. Also the energy savings obtained are suboptimal.